(a) Field of Invention
The present invention relates to hand tools for displacing relatively heavy objects and concerns more particularly an improved levering tool generally useful in displacing such objects in a safe and easy manner. More specifically, that new tool is to be used to lift and displace manhole covers or lids from their housing and also to drag them along a distance to clear the manhole. The same tool also serves to drag the cover back over the manhole to its initial position.
(b) Description of Prior Art
The operation of lifting a cover for clearing a manhole inlet may appear a rather simple and a common place operation. It is to be noted, however, that most of those manhole covers are made of cast iron the appropriate weight of which ranges from 140 kilograms to 180 kilograms and that the clearance between the cover edge and the inner rim of the manhole cover support and housing is substantially low so that appropriate tools are required by workers to handle those awkward pieces. To do so, simple hooks are usually used by workers where the hooks are inserted into holes provided into the cover. That method asks for considerable effort from the worker who, at the start, has to lean forward with his feet apart from one another and close to the manhole outer edge to pull the cover from its housing. This strains the arm, shoulder and back muscles. Moreover, additional efforts have to be supplied by the worker since most frequently rust or ice (usual in northern areas) could be formed between the cover and the manhole support surface. Those characteristics result in a number of injuries which are often encountered by the worker, such as sore back, muscular strains, directly related to the efforts supplied, or from injuries resulting from the slippage of the manhole on a foot where the work is performed on loose soil or slippery surfaces.
To minimize those hazards as well as the effort necessary to lift up manhole covers, some levering tools were proposed. One solution comprises a lever having two rods linked together, one rod being positioned vertically and resting against the cover at a point slightly inside the peripheral edge thereof, whereas the other rod is hooked into a hole provided in the cover at a point opposite to the vertical rod fulcrum. Thus, by applying a force upon the vertical rod, it is possible to raise the cover and rock it outside its housing. However, the worker still has to supply considerable effort to perform the operation and the method is rather unsafe since at the start he must lean forward whereas he has to tilt backward when the cover is rocked, thereby increasing the slippage hazard. Moreover, a lateral effort has to be provided to pull the cover aside and away from the manhole inlet while maintaining same lifted. For those reasons, that device has not proven satisfactory.
Another type of lever was also proposed for the same purpose. The latter is made up of a slightly upwardly bent rigid rod one extremity of which is so shaped as to be inserted into a hole provided into a cover. At a given distance from the inserted extremity, there is set a bearing wheel acting as the fulcrum so that an action onto the free end of the rod allows to lift the cover which may be dragged away from the inlet by pulling the rod, which therefore requires a double effort and action from the worker. Moreover, when the cover is lifted, the above setting becomes out of balance since a light lateral movement from the worker causes the wheel to tip over. Additionally, that type of lever cannot be used where the surface immediately adjacent the manhole is covered with snow, grass, loose soil or when the surrounding ground surface is at a lower level than the cover surface.